Roberts, who happens to be an avid runner, says Roker, 56, has been practicing over long miles with a trainer. "It's such a sore subject in my house," she says about the light-hearted competition between them. "I've been running for 30 years, and I have a knee injury. He started a year ago, and he's doing fine."

For his part, Roker – who says he is "down to a 13-minute mile [though] I still get passed by grandparents" – tells PEOPLE he has yet to experience what is called the runner's high.

"I don't enjoy running," he admits. "Somebody told me that running is 20 percent physically and 80 percent mental. I feel that if I'm running six miles, that sixth mile is the hardest. If I'm doing eight miles, the eighth mile is the hardest. I don't know – it's this weird thing."

Even so, come the big race on Nov. 7, Roberts looks forward to rooting Roker on near the Central Park finish line.

"God bless him. I think it's great," she says. "This is his project, and I'll be there to cheer him on with a sign and to resuscitate him if need be – but I don't think I need to. I think he'll do just fine."